Vacuum toilet discharge systems often present problems because their components become stuck together, following different periods of inactivity. One of the components which usually suffers most in this respect is the shutoff valve. This is usually due to the fact that the substances which are in the water, such as lime and the like, often build up scale between the fixed and moving parts of the valve, hindering or even blocking its operation; moreover, if solid particles come between the fixed and moving parts the operation of the valve can become defective, leading to leaks, defective movements, abrasion, etc.
Where a toilet discharge system remains inactive for some time, the shutter member of the shutoff valve can easily adhere to its housing due to the remains of lime and the like, so that in the next operation cycle the normal driving system does not have sufficient force to move the shutter member; in such cases, the valve remains inoperative and has to be disassembled for cleaning, with the attendant disadvantages of down-time due to breakdown, labour cost, etc.
Another disadvantage of toilet discharge systems having valves with a moving part is that lubrication of the unit is sometimes insufficient, and this also has a negative effect on operation of the valve.
One example of a toilet discharge system with shutoff valve to which this invention can be applied is described in Spanish patent ES-A-2072176, in the name of the same Applicant.